Device and method for extracting potato protein

Abstract

A device for extracting protein from potatoes, the device comprising: a first filtration device containing a filtration material having a first pore size; a second filter device containing a filter material having a second aperture; a third filter device containing a filter material having a third aperture; the second aperture is smaller than the first aperture, and the third aperture is smaller than the second aperture.

Description

Technical Field

[0001] The present invention relates to a device and method for extracting potato protein. More specifically, the present invention relates to a device and method for extracting potato protein, wherein the protein is extracted by filtering through multiple filtering devices. Background Art

[0002] Protein is an important component of daily dietary requirements. Protein is required for various important biological processes, including muscle synthesis, DNA replication, catalysis of metabolic reactions, etc. Lack of protein intake can lead to serious conditions such as muscle atrophy and liver failure. In recent years, vegetarianism has been on the rise for reasons such as animal welfare, environmental issues related to agriculture, lactose intolerance and weight management. Therefore, the market for providing plant-based proteins has flourished. Potatoes contain proteins whose nutritional value can replace animal proteins such as those from meat, eggs, milk, etc.

[0003] Potato protein is usually obtained from potato juice. It is known to extract protein from said potato juice using filtration methods. A disadvantage associated with such known methods is that the filtration apparatus can become contaminated by particles in the potato juice, limiting production efficiency. The filters need to be cleaned or replaced, which can result in downtime and / or increased costs.

[0004] It is therefore a non-exclusive object of the present invention to overcome or at least significantly alleviate one or more problems associated with the prior art. Summary of the invention

[0005] According to a first aspect, the present invention provides a device for extracting protein from potatoes, the device comprising: a first filtering device containing a filtering material having a first pore size; a second filtering device containing a filtering material having a second pore size; a third filtering device containing a filtering material having a third pore size; and an ultrafiltration device, wherein the second pore size is smaller than the first pore size, and the third pore size is smaller than the second pore size.

[0006] The first filter device, the second filter device and / or the third filter device may be integrated into a single unit. Alternatively, the first filter device, the second filter device and / or the third filter device may be discrete (independent) units.

[0007] The apparatus of the present invention may also include a decanter centrifuge and / or a sedimentation vessel for clarifying the potato juice. Clarification is the process of separating insoluble particles from a liquid. In the method of the present invention, the potato juice is clarified to obtain clarified potato juice.

[0008] The first aperture can be 10 microns to 200 microns, for example 10 microns to 100 microns, for example 10 microns to 50 microns, for example 25 microns to 50 microns. For example, the first aperture can be 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns, 60 microns, 65 microns, 70 microns, 75 microns, 80 microns, 85 microns, 90 microns, 95 microns, 100 microns, 105 microns, 110 microns, 115 microns, 120 microns, 125 microns, 130 microns, 135 microns, 140 microns, 145 microns, 150 microns, 155 microns, 160 microns, 165 microns, 170 microns, 175 microns, 180 microns, 185 microns, 190 microns, 195 microns or 200 microns.

[0009] The second pore size may be 0.8 μm to 10 μm, such as 0.8 μm to 5 μm, such as 0.8 μm to 4 μm, such as 0.8 μm to 3 μm, such as 0.8 μm to 2 μm. For example, the second pore size can be 0.8 micrometers, 1.0 micrometers, 1.2 micrometers, 1.4 micrometers, 1.6 micrometers, 1.8 micrometers, 2.0 micrometers, 2.2 micrometers, 2.4 micrometers, 2.6 micrometers, 2.8 micrometers, 3.0 micrometers, 3.2 micrometers, 3.4 micrometers, 3.6 micrometers, 3.8 micrometers, 4.0 micrometers, 4.2 micrometers, 4.4 micrometers, 4.6 micrometers, 4.8 micrometers, 5.0 micrometers, 5.2 micrometers, 5.4 micrometers, 5.6 micrometers, 5.8 micrometers, 6.0 micrometers, 6.2 micrometers, 6.4 micrometers, 6.6 micrometers, 6.8 micrometers, 7.0 micrometers, 7.2 micrometers, 7.4 micrometers, 7.6 micrometers, 7.8 micrometers, 8.0 micrometers, 8.2 micrometers, 8.4 micrometers, 8.6 micrometers, 8.8 micrometers, 9.0 micrometers, 9.2 micrometers, 9.4 micrometers, 9.6 micrometers, 9.8 micrometers or 10 micrometers.

[0010] The third pore size can be less than 0.8 micron, for example, from 0.1 micron to less than 0.8 micron, for example, from 0.2 micron to 0.7 micron, for example, from 0.3 micron to 0.6 micron, for example, from 0.4 micron to 0.5 micron. For example, the third pore size can be 0.1 micron, 0.2 micron, 0.3 micron, 0.4 micron, 0.5 micron, 0.6 micron or 0.7 micron.

[0011] The ultrafiltration device may comprise a tangential flow ultrafiltration device.

[0012] The ultrafiltration device may include one or more filter membranes having a molecular weight cutoff of 5 kDa to 150 kDa, such as 5 kDa to 100 kDa, such as 5 kDa to 50 kDa, such as from 5 kDa to 25 kDa, such as from 5 kDa to 10 kDa. For example, the molecular weight cutoff may be 5 kDa, 10 kDa, 15 kDa, 20 kDa, 25 kDa, 30 kDa, 35 kDa, 40 kDa, 45 kDa, 50 kDa, 55 kDa, 60 kDa, 65 kDa, 70 kDa, 75 kDa, 80 kDa, 85 kDa, 90 kDa, 95 kDa, 100 kDa, 105 kDa, 110 kDa, 115 kDa, 120 kDa, 125 kDa, 130 kDa, 135 kDa, 140 kDa, 145 kDa or 150 kDa.

[0013] The membrane surface area of ​​the or each filter membrane may be 3.5 m 2 -40m 2 For example, the membrane surface area of ​​each filter membrane can be 4.1m 2 . The filter membrane or each filter membrane may be made of polyethersulfone on a polyester substrate. The maximum operating temperature of the filter membrane or each filter membrane may be 50°C-85°C. The maximum operating pressure of the filter membrane or each filter membrane may be 970kPa. The filter membrane or each filter membrane may be a spiral membrane filter. In some examples, the ultrafiltration device may include multiple (e.g., 2) spiral membrane filters.

[0014] The filter material of any one or more of the first filter device, the second filter device and the third filter device may be in the form of a bag filter.

[0015] The bag filter or bag filters can withstand temperatures of up to 150°C, for example up to 95°C. The bag filter or bag filters can withstand pressure differences of up to about 100 kPa. The bag filter or bag filters may have a generally circular opening with a diameter of, for example, about 0.1 m to 0.2 m. For example, the diameter may be 0.102 m or 0.178 m. The bag filter may have a length of about 0.2 m to 1 m. For example, the length may be 0.229 m, 0.356 m, 0.406 m or 0.813 m. The total area of ​​the filter material of the bag filter or bag filters may be 0.05 m 2 Up to 0.5m 2 The total area may be, for example, 0.07 m 2 、0.12m 2 、0.23m 2 or 0.41m 2In one example, the diameter of the bag filter may be 0.178 m, the length may be 0.406 m, and the total area may be 0.23 m 2 .

[0016] Any one or more of the first filter device, the second filter device and the third filter device may include or consist of a centrifugal separator, wherein the centrifugal separator comprises:

[0017] a housing having: an inlet for receiving potato juice, a first outlet, and a second outlet;

[0018] an element configured to rotate relative to the housing to generate a centrifugal force within the housing;

[0019] and filter materials of the first filter device, the second filter device and / or the third filter device,

[0020] The first outlet is configured to receive retentate retained by the filter material, and the second outlet is configured to receive filtrate passed through the filter material.

[0021] In some examples, the filter material can be in the form of a woven or non-woven fabric, such as felt. In some examples, the filter material can be a mesh, a mesh, or a porous structure. The filter material can be made of polypropylene, polyester, nylon, a porous polytetrafluoroethylene (PTFE) film, a fluoropolymer, viscose fiber, aromatic polyamide, wool, stainless steel, or a combination thereof. It is readily understood by those skilled in the art that other materials can also be used to form the filter material, and this list of materials is not exhaustive.

[0022] The filter material of any one or more of the first filter device, the second filter device and the third filter device may include one or more layers, for example, up to ten layers. For example, the filter material of any filter device may include one, two, three, four, five, six, seven, eight, nine or ten layers.

[0023] The filter material of the first filter means and / or the filter material of the second filter means may comprise one layer.

[0024] The filter material of the third filter means may include two or more layers.

[0025] When the filter material of any one of the first filter means, the second filter means and the third filter means comprises two or more layers, the layers may have different pore sizes. For example, the layers may have pore sizes that gradually decrease from a first side of the filter material to a second side of the filter material opposite to the first side. In such an example, the pore size of the filter material is equivalent to the pore size of the filter material layer having the smallest pore size.

[0026] The apparatus of the present invention may also include a drying device for drying potato protein. The drying device may include any one or a combination of a spray dryer, a freeze dryer or an atmospheric belt dryer. In an example including a spray dryer, the spray dryer may include a nozzle operable to spray a fluid into a hot gas stream. The temperature of the hot gas stream may range from 120° C. to 600° C. In an example including a freeze dryer, the temperature of the freeze dryer may range from -50° C. to -80° C. It will be appreciated by those skilled in the art that alternative drying methods may also be used.

[0027] According to a second aspect, the present invention provides a method for extracting protein from potatoes, the method comprising:

[0028] (a) obtaining potato juice;

[0029] (b) passing the potato juice through a first filtering device having a filtering material with a first pore size to obtain a first filtrate;

[0030] (c) passing the first filtrate through a second filtration device having a filter material with a second pore size to obtain a second filtrate;

[0031] (d) passing the second filtrate through a third filtration device having a filter material with a third pore size to obtain a third filtrate; and

[0032] (e) subjecting the third filtrate to ultrafiltration to obtain an ultrafiltration retentate,

[0033] The second aperture is smaller than the first aperture, and the third aperture is smaller than the second aperture.

[0034] The method may further include drying the ultrafiltration retentate to produce potato protein.

[0035] The drying step may produce a powder containing greater than 65 wt % native potato protein, e.g., greater than 70 wt % native potato protein, e.g., greater than 75 wt % native potato protein, e.g., greater than 80 wt % native potato protein, e.g., greater than 85 wt % native potato protein, e.g., greater than 90 wt % native potato protein, e.g., greater than 95 wt % native potato protein.

[0036] The first aperture can be 10 microns to 200 microns, for example 10 microns to 100 microns, for example 10 microns to 50 microns, for example 25 microns to 50 microns. For example, the first aperture can be 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns, 60 microns, 65 microns, 70 microns, 75 microns, 80 microns, 85 microns, 90 microns, 95 microns, 100 microns, 105 microns, 110 microns, 115 microns, 120 microns, 125 microns, 130 microns, 135 microns, 140 microns, 145 microns, 150 microns, 155 microns, 160 microns, 165 microns, 170 microns, 175 microns, 180 microns, 185 microns, 190 microns, 195 microns or 200 microns.

[0037] The second pore size may be 0.8 μm to 10 μm, such as 0.8 μm to 5 μm, such as 0.8 μm to 4 μm, such as 0.8 μm to 3 μm, such as 0.8 μm to 2 μm. For example, the second pore size can be 0.8 micrometers, 1.0 micrometers, 1.2 micrometers, 1.4 micrometers, 1.6 micrometers, 1.8 micrometers, 2.0 micrometers, 2.2 micrometers, 2.4 micrometers, 2.6 micrometers, 2.8 micrometers, 3.0 micrometers, 3.2 micrometers, 3.4 micrometers, 3.6 micrometers, 3.8 micrometers, 4.0 micrometers, 4.2 micrometers, 4.4 micrometers, 4.6 micrometers, 4.8 micrometers, 5.0 micrometers, 5.2 micrometers, 5.4 micrometers, 5.6 micrometers, 5.8 micrometers, 6.0 micrometers, 6.2 micrometers, 6.4 micrometers, 6.6 micrometers, 6.8 micrometers, 7.0 micrometers, 7.2 micrometers, 7.4 micrometers, 7.6 micrometers, 7.8 micrometers, 8.0 micrometers, 8.2 micrometers, 8.4 micrometers, 8.6 micrometers, 8.8 micrometers, 9.0 micrometers, 9.2 micrometers, 9.4 micrometers, 9.6 micrometers, 9.8 micrometers or 10 micrometers.

[0038] The third pore size can be less than 0.8 micron, for example, from 0.1 micron to less than 0.8 micron, for example, from 0.2 micron to 0.7 micron, for example, from 0.3 micron to 0.6 micron, for example, from 0.4 micron to 0.5 micron. For example, the third pore size can be 0.1 micron, 0.2 micron, 0.3 micron, 0.4 micron, 0.5 micron, 0.6 micron or 0.7 micron.

[0039] The potato juice may be clarified before passing through the first filtering device.

[0040] The potato juice may be clarified using either or both of sedimentation and precipitation techniques well known to the skilled artisan.

[0041] Step (e) of the method may involve diafiltration of the ultrafiltration retentate using conventional techniques. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Specific embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0043] Figure 1 A schematic diagram of a protein extraction device provided in Example 1 of the present invention;

[0044] Figure 2 A schematic diagram of a protein extraction device provided in Example 2 of the present invention;

[0045] Figure 3 is a schematic side view of a cross section of a centrifugal separator of the present invention; and

[0046] Figure 4 Schematic diagram of an explosion of a filter material including multiple layers according to the present invention. DETAILED DESCRIPTION

[0047] refer to Figure 1 , shows a device 1 for extracting protein according to Example 1 of the present invention. The device 1 comprises a first filter device 10 having a filter material 12 of a first pore size, a second filter device 20 having a filter material 22 of a second pore size, and a third filter device 30 having a filter material 32 of a third pore size.

[0048] Any one of the first filter device 10, the second filter device 20 and the third filter device 30 may include or consist of a centrifugal separator 14. Specifically, the first filter device 10 may be a centrifugal separator 14.

[0049] refer to Figure 3, the centrifugal separator 14 may include a housing 140, an element 148 configured to rotate relative to the housing 140 to generate centrifugal force in the housing 140, and a filter material 12 (in the example, the first filter device 10 is a centrifugal separator 14). The housing 140 may be a generally cylindrical shape having a central axis A. The filter material 12 may be concentrically positioned in the housing 140. The filter material 12 may be a wire mesh formed by, for example, stainless steel. The pore size of the filter material 12 may be 25 microns or 50 microns. The housing 140 may have an inlet 142 for receiving potato juice, a first outlet 144, and a second outlet 146. During use, the element 148 may be configured to rotate about the axis A to generate a vortex in the housing 140. The filtrate (i.e., liquid and particles that can pass through the filter material 12) is sucked along the vortex and leaves the housing 140 from the second outlet 146. The retentate (i.e., particles that are too large to pass through the filter material 12) leaves the housing from the first outlet 144. The capacity of the housing 140 may be 1.6 m 3 Illustratively, the centrifugal separator 14 may be a model manufactured by Russell Finex.

[0050] Reference again Figure 1 The filter materials 22, 32 of the second filter device 20 and the third filter device 30, respectively, may be in the form of bag filters.

[0051] The filter material 22 (bag filter) of the second filter device 20 can be made of polypropylene felt with a pore size of 1 micron. The filter material 22 can be a single layer. Exemplarily, the bag filter can be a type manufactured by Fileder Filter Systems, and its part number is EBSP-1-1.

[0052] The filter material 32 (bag filter) of the third filter device 30 can be made of polypropylene felt with a pore size of 0.5 microns. The filter material 32 can have five layers. Exemplarily, the bag filter can be a type manufactured by Fileder Filter Systems, and its part number is PBP-0.5-1.

[0053] Reference now Figure 4 , shows an exploded schematic diagram of the filter material 32. The filter material 32 has a first side 320 and a second side 322 opposite the first side 320. The filter material 32 may include five layers 32a-e having different pore sizes 34a-e. The five layers 32a-e may have pore sizes that gradually decrease from the first side 320 to the second side 322. The pore size of the filter material 32 (i.e., 0.5 microns) is equivalent to the pore size of the layer 34e with the smallest pore size.

[0054] Reference again Figure 1, the apparatus 1 may further comprise one or more containers 50 for clarifying the potato juice. The one or more containers 50 may comprise either or both of a decanter centrifuge or a sedimentation container.

[0055] The device 1 may further comprise an ultrafiltration device 40. The ultrafiltration device may comprise two or more spiral membrane filters with a molecular weight cut-off of 10 kDa.

[0056] The device 1 may also comprise drying means 60 in the form of a spray dryer.

[0057] A method for extracting potato protein using the apparatus 1 is now described. 1500 kg of potatoes are sterilized and loaded into a rasp (not shown) where the potatoes are broken down into potato pulp. Water is added to the potato pulp to form potato pulp juice. The volume ratio of water to potato pulp may be from 1:2 to 1:1. For example, 1000 liters of water may be mixed with 1000 liters of potato pulp to form 2000 liters of potato juice. A preservative such as sodium metabisulfite may also be added. Alternatively, potato juice may be obtained from other sources. For example, potato juice may be obtained directly from a potato chip production facility or the like.

[0058] The potato juice is then fed into the container or containers 50 to obtain clarified potato juice. Alternatively, clarified potato juice may be obtained from other sources.

[0059] The clarified potato juice is then fed to a first filtering device 10, which may be in the form of a centrifugal separator 14. The centrifugal separator 14 separates particles having a size greater than 50 microns. Figure 3 , the clarified potato juice is fed into the housing 140 through the inlet 142. The element 148 located inside the centrifugal separator 14 rotates the clarified potato juice relative to the housing 140 so that the centrifugal force generates a vortex. The filter membrane 12 prevents particles with a particle size greater than 50 microns from passing through. The retentate exits the housing at the first outlet 144. The rest is sucked along the vortex and leaves the housing 140 at the second outlet 146 to obtain the first filtrate.

[0060] The first filtrate is then sent to a second filter device 20, which may be in the form of a bag filter. The second filter device 20 has a filter material 22 with a pore size of 1 micron. The first filtrate enters the second filter device 20 at a pressure of about 230 kPa, and the first filtrate passes through the filter material 22 of the second filter device 20 to remove particles with a particle size greater than 1 micron, thereby obtaining a second filtrate.

[0061] The second filtrate is then fed into a third filter device 30, which may be in the form of a bag filter. The filter material 32 of the bag filter may include five layers and may have a minimum pore size of 0.5 microns. The second filtrate enters the third filter device 30 at a pressure of about 230 kPa. Referring to FIG. 5 , the second filtrate flows from the first side 320 to the second side 322 in the direction of the arrow. When the second filtrate flows through the five layers 32a-e, each of the five layers 32a-e retains particles having a particle size greater than its respective pore size 34a-e, thereby obtaining a third filtrate.

[0062] The third filtrate is then sent to an ultrafiltration device 40 to obtain an ultrafiltration retentate. Alternatively, pure water or a buffer solution may be used for diafiltration in the ultrafiltration process according to known methods.

[0063] The ultrafiltration retentate is then fed to a drying device 60, which may be in the form of a spray dryer. The ultrafiltration retentate is sprayed into a stream of hot air to obtain a powder containing more than 70% by weight of native potato protein.

[0064] refer to Figure 2 , shows an apparatus 1' for extracting proteins according to Example 2 of the present invention. Parts of the apparatus 1' similar to those of the apparatus 1 in Example 1 are given the same numbers but are marked with a prime (').

[0065] The device 1 ' comprises a first filter device 10' having a filter material 12' of a first pore size, a second filter device 20' having a filter material 22' of a second pore size, and a third filter device 30' having a filter material 32' of a third pore size.

[0066] The filter materials 12 ′, 22 ′, 32 ′ of each of the second filter device 10 ′, the second filter device 20 ′ and the third filter device 30 ′ may be in the form of bag filters.

[0067] The filter material 12' (bag filter) of the first filter device 10' can be made of polypropylene felt with a pore size of 0.5 microns. The filter material 12' can be a single layer. Exemplarily, the bag filter can be a type manufactured by Fileder Filter Systems, and its part number is EBSP-50-1.

[0068] The filter material 22' (bag filter) of the second filter device 20' can be made of polypropylene felt with a pore size of 1 micron. The filter material 22' can be a single layer. Exemplarily, the bag filter can be a type manufactured by Fileder Filter Systems, and its part number is EBSP-1-1.

[0069] The filter material 32' (bag filter) of the third filter device 30' can be made of polypropylene felt with a pore size of 0.5 microns. The filter material 32' can be five layers. Exemplarily, the bag filter can be a type manufactured by Fileder Filter Systems, and its part number is PBP-0.5-1.

[0070] The device 1' may further include an ultrafiltration device 40'. The ultrafiltration device may include two or more spiral membrane filters with a molecular weight cut-off of 10 kDa.

[0071] The device 1 ' may also comprise drying means 60' in the form of a spray dryer.

[0072] Now, a method for extracting potato protein using the device 1' is described. Clarified potato juice is obtained and sent to a first filtering device 10'. The potato juice enters the first filtering device 10' at a pressure of about 230 kPa. The clarified potato juice passes through the filtering material 12' of the first filtering device 10' to remove particles with a particle size greater than 50 microns, thereby obtaining a first filtrate.

[0073] The first filtrate is then sent to a second filter device 20', which may be in the form of a bag filter. The second filter device 20' has a filter material 22' with a pore size of 1 micron. The first filtrate enters the second filter device 20' at a pressure of about 230 kPa, and the first filtrate passes through the filter material 22' of the second filter device 20' to remove particles with a particle size greater than 1 micron, thereby obtaining a second filtrate.

[0074] The second filtrate is then sent to a third filter device 30', which may be in the form of a bag filter. The filter material 32' of the bag filter may include five layers and may have a minimum pore size of 0.5 microns. The second filtrate enters the third filter device 30' at a pressure of about 230 kPa. The second filtrate passes through the filter material 32' of the third filter device 30' to remove particles with a particle size greater than 0.5 microns, thereby obtaining a third filtrate.

[0075] The third filtrate is then sent to an ultrafiltration device 40' to obtain an ultrafiltration retentate. Alternatively, pure water or a buffer solution may be used for diafiltration in the ultrafiltration process according to known methods.

[0076] The ultrafiltration retentate is then fed to a drying device 60', which may be in the form of a spray dryer. The ultrafiltration retentate is sprayed into a stream of hot air to obtain a powder containing more than 70% by weight of native potato protein.

[0077] The following advantages of the present invention are apparent.

[0078] Compared with prior art methods, fouling of the filter membrane is significantly reduced.

[0079] Applicants estimate that approximately 25 times more protein can be passed through the filter membrane using the scheme of the present invention compared to prior art methods, without requiring much downtime in the production. This can increase the flow rate of potato juice through the device 1, 1', which means that the present invention can produce protein at a faster rate compared to prior art methods. In particular, by performing three filtration stages before the ultrafiltration stage, protein contamination can be reduced. Therefore, the device 1, 1' of the present invention can achieve reliable production rates with minimal interruptions.

[0080] The native potato protein obtained according to the process described herein is a functional, clean label protein. In other words, the protein contains many of the natural bioactive components required to support and maintain a healthy immune system.

[0081] In the present invention, the terms "include" and "comprising" and their variations mean including the specified features, steps or integral parts. These terms should not be interpreted as excluding the existence of other features, steps or components.

[0082] The present invention may also broadly include parts, elements, steps, examples and / or features mentioned or indicated individually or collectively in the specification, which may exist in the form of any and all combinations of two or more of the parts, elements, steps, examples and / or features. Specifically, one or more features in any example described herein may be combined with one or more features in any other example described herein.

[0083] Protection may be sought for any feature disclosed in any one or more of the publications cited herein in conjunction with the present invention.

[0084] Although certain examples of the invention have been described, the scope of the invention is not intended to be limited to only these examples.

Claims

1. A device for extracting protein from potatoes, the device comprising: a first filter device comprising a filter material having a first pore size; a second filter device comprising a filter material having a second pore size; a third filter device comprising a filter material having a third pore size; as well as Ultrafiltration device; The second aperture is smaller than the first aperture, and the third aperture is smaller than the second aperture.

2. The device according to claim 1, further comprising any one or both of a decanter centrifuge and a sedimentation container.

3. A device according to any one of the preceding claims, wherein: The first pore size is 10 micrometers to 200 micrometers.

4. A device according to any one of the preceding claims, wherein: The second pore size is 0.8 micrometer to 10 micrometers.

5. A device according to any one of the preceding claims, wherein: The third pore size is less than 0.8 micrometers.

6. The device according to claim 5, wherein: The third pore size is 0.1 micrometer or larger.

7. A device according to any one of the preceding claims, wherein: The ultrafiltration device comprises a filter membrane with a molecular weight cut-off of 5 kDa to 150 kDa.

8. A device according to any one of the preceding claims, wherein: The filter material of any one or more of the first filter device, the second filter device and the third filter device is in the form of a bag filter.

9. The device according to any one of claims 1 to 8, wherein: The first filtering device comprises or consists of a centrifugal separator, wherein the centrifugal separator comprises: A housing, the housing comprising: an inlet for receiving potato juice; First exit; and Second exit; an element configured to rotate relative to the housing to generate a centrifugal force within the housing; and the filter material of the first filter device, wherein the first outlet is configured to receive a retentate retained by the filter material, and the second outlet is configured to receive a filtrate passed through the filter material.

10. The device according to claim 9, wherein the filter material of the second filter device and / or the filter material of the third filter device is in the form of a bag filter.

11. A device according to any one of the preceding claims, the filter material of any one or more of the first filter means, the second filter means and the third filter means comprising one or more layers.

12. The device according to claim 11, wherein The filter material of the first filter device and / or the filter material of the second filter device comprises one layer.

13. The device according to claim 11 or 12, wherein the filter material of the third filter means comprises two or more layers.

14. The device according to any one of claims 11 to 13, wherein: When the filter material of any one of the first filter device, the second filter device, and the third filter device includes two or more layers, each layer has a different pore size.

15. The device according to claim 14, wherein: The filter material of any one of the first filter device, the second filter device and the third filter device includes a first side and a second side opposite to the first side, wherein each layer has a pore size that gradually decreases from the first side to the second side.

16. Apparatus according to any one of the preceding claims, further comprising drying means for drying potato protein.

17. A method for extracting protein from potatoes, the method comprising: (a) obtaining potato juice; (b) passing the potato juice through a first filtering device having a filtering material with a first pore size to obtain a first filtrate; (c) passing the first filtrate through a second filtration device having a filter material with a second pore size to obtain a second filtrate; (d) passing the second filtrate through a third filtration device having a filter material with a third pore size to obtain a third filtrate; as well as (e) subjecting the third filtrate to ultrafiltration to obtain an ultrafiltration retentate, The second aperture is smaller than the first aperture, and the third aperture is smaller than the second aperture.

18. The method of claim 17, further comprising drying the ultrafiltration retentate to produce the potato protein.

19. The method according to claim 17 or 18, wherein: The first pore size is 10 micrometers to 200 micrometers.

20. The method according to any one of claims 17 to 19, wherein: The second pore size is 0.8 micrometer to 10 micrometers.

21. The method according to any one of claims 17 to 20, wherein: The third pore size is less than 0.8 micrometers.

22. The method according to claim 21, wherein: The third pore size is 0.1 micrometer or larger.

23. The method according to any one of claims 17 to 22, wherein: The potato juice is clarified before passing through the first filtering device.

24. The method according to claim 23, wherein: The potato juice is clarified using a sedimentation centrifuge or a sedimentation vessel.

25. The method according to any one of claims 17 to 24, wherein: The step (e) involves subjecting the ultrafiltration retentate to diafiltration.

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